Last month as citizens were munching on barbecued ribs and corn on the cob at Mayor Jane Byrne's Taste of Chicago festival, a light plane swooped down on the gathering, trailing an impertinent message: ''Draft Daley for Mayor.''
Chicago's mayoral primary is still six months away. But Mayor Byrne is acting as if it were coming up tomorrow. And the failure of Cook County State's Attorney Richard M. Daley, son of the late mayor and Mrs. Byrne's likely chief rival, to come forward and declare his candidacy clearly nettles her.
Discounting any knowledge of or approval of the aerial banner, the state's attorney says he will not announce his decision until after the November elections. True, Mr. Daley is sponsoring a $100-a-plate fund-raiser at the end of August. But he says he will return the money if he decides not to run.
Mayor Byrne, who managed a surprise win on her first try for elective office, against incumbent Democratic Mayor Michael Bilandic in 1979, considers the city's late, long-reigning mayor, Richard J. Daley, a mentor. But she and his son squared off early as political foes. She supported his Democratic opponent for state's attorney and accused him of condoning a racist scheme in the city building department with respect to his own southwest ward. Mr. Daley, in turn, accused her of ''McCarthyism.''
A Chicago Tribune poll in July put Mayor Byrne three points behind in a two-way race with Daley. A similar poll last January had her trailing by eight points. If others enter the Democratic primary (possible contenders include Rep. Harold Washington, Rep. Dan Rostenkowski, and Alderman Roman Pucinski), the mayor is expected to fare better. But Daley could opt to postpone the battle by staying out of the Feb. 22 primary and running as an independent in the April 12 election.
The uncertain list of candidates and Daley's choice of timing are only two of many imponderables still hovering over Chicago's 1983 mayoral election. ''It's a wide-open ball game,'' insists Milton Rakove, a University of Illinois political science professor and a veteran analyst of Chicago elections.
One of the biggest question marks is what the city's black voters will do. Though she earned strong credits with many of them by moving briefly into the crime-ridden Cabrini-Green housing project and could not have won the 1979 election without the support of South Side blacks, Mayor Byrne has antagonized many black voters by her failure to appoint more of them to top city positions.
Her recent appointment of three whites to the Chicago Housing Authority (CHA) board, which serves an 84 percent black population, tipped the racial balance of the board and set off numerous protests. These included an effective black boycott of Mayor Byrne's annual Chicagofest on Navy Pier. Her order for massive school spending cuts and appointment of two whites opposed to busing as replacements for two blacks on Chicago's school board a few years ago sparked a similar outcry.
''I don't think she's given up on poor blacks in the city, but I think she's dead with middle-class blacks,'' comments Dr. Rakove. ''She seems to have cast her lot pretty much with white ethnics.''
Many black leaders talk of putting up their own candidate. Representative Washington is considered the most viable choice. But he won't run unless convinced he will fare well. Though blacks account for about half of Chicago's population, they account for only 30 percent of the electorate.
Although the late Mayor Daley did not particularly endear himself to the city's black community, his son, according to recent polls, is more popular with black voters than Mayor Byrne.
Still, regulars of the Democratic Party ''organization,'' entrenched in many Chicago wards, may not be all that ready to exchange a Byrne for another Daley. Prof. Larry Bennett, a De Paul University political scientist, notes that the spoils of political patronage have been more widespread in city wards since the passing of Mayor Daley, who showered many of them on his own 11th Ward.
''It (Daley's win) wouldn't be like the return of a deposed king,'' insists Professor Bennett.
Polls suggest that a majority of voters view Mayor Byrne as a capable administrator. But they give her less-than-stellar marks for her often volatile approach to making personnel changes. Bennett attributes some of that to her needs as an outsider to shore up her political base.
Whatever the justification, it is sure to become a campaign issue. Mayor Byrne, who was able to throw the darts at her opponent the last time around for a less than efficient snow removal job, will this time be on the defending end.